(string)
Repository from which to install. May be one of the following:
distro (default), ppa:somecustom/ppa, a deb url sources entry,
or a supported Cloud Archive release pocket.
Supported Cloud Archive sources include:
cloud:<series>-<openstack-release>
cloud:<series>-<openstack-release>/updates
cloud:<series>-<openstack-release>/staging
cloud:<series>-<openstack-release>/proposed
For series=Precise we support cloud archives for openstack-release:
* icehouse
For series=Trusty we support cloud archives for openstack-release:
* juno
* kilo
NOTE: this option must be set before install.